AMBRIDGE, Pa. (KDKA/AP) – A 15-year-old boy was taken into police custody after a knife was found in his backpack today while police were conducting a search of Ambridge High School in Beaver County.

According to Ambridge Police Chief James Mann, the boy is facing charges of risking or creating a catastrophe, possession of a weapon and disorderly conduct.

He was first taken to the Beaver County Jail and now is being transferred to a juvenile detention center in Steubenville, Ohio.

Chief Mann said it all started earlier in the day when a few students and a school resource officer found a message saying, “I have a gun” written in pencil on the wall in the boy’s bathroom next to the lunch room.

(Source: Ambridge Police Chief James Mann)

Police were called in, locked down the school and began a search of the building, including the backpack, purse and locker of each student.

During that search, Chief Mann said they found a 14-inch knife in the unidentified boy’s backpack.

According to investigators, he told them he had been in an altercation a few weeks before and said he was carrying the knife for his protection. The boy also told them he forgot he had it, police said.

Ambridge School District officials say the knife discover and message scrolled on the bathroom wall are unrelated incidents.

Police in Ambridge say they are concerned because all students pass through metal detectors and are wanded at the school, but the knife was not detected.

In addition to Ambridge Police, the Harmony Township, Baden, Conway and Economy Borough police departments assisted with the search during the lockdown.

Ambridge School District Superintendent Dr. Cynthia Zurchin released a statement following the incident. It reads in part:

“Safety is a number one priority in the Ambridge Area School District. I am very impressed by the response of our local authorities and all emergency personnel across the region. A note huge note of ‘thank you’ goes out to Ambridge Police Chief, Officer James Mann who handled the full investigation and searches both professionally and timely. All parents of the high school were notified immediately of the situation through the school district’s “Bridger Broadcast” system, a school to phone message system for parents of the district.:

Authorities cleared the school around 12:15 p.m.

No gun was ever found. There’s also no word on who wrote the note in the boy’s bathroom stall.

On April 9, a student at Franklin Regional High School in Murrysville was charged with attempted homicide and aggravated assault after he allegedly used two kitchen knives from his home to stab 20 students and a security guard.